Structural restriction in the heavy chain CDR3 of human rheumatoid factors

We have compared the variable regions of 14 new IgM rheumatoid factors (RFs), produced in healthy human immunized donors (HIDs) with RFs originating from patients with rheumatoid arthritis (RA) and monoclonal Ig RFs (paraproteins or M-components, MC). Two groups with very restricted variable region structures were found. Twelve RFs (3 HID, 3 MC, and 6 RA) encoded by variable heavy (VH) chain germ-line genes with closest homology to DP-10 co-express the Kv325 variable light (VL) chain germ-line gene. These RFs have a remarkable restriction in the length (12-14 amino acids) and structure of the CDRH3. One HID RF has a CDRH3 only two amino acids different from the CDRH3 of a MC RF. Two sets of clonally related RFs, one from an RA patient and one from an HID, have CDRH3s that differ by only three amino acids. Five RFs (3 HID, 1 MC, and 1 RA) encoded by VH germ-line gene segments with closest homology to DP-54 all use the Kv328 VL germ-line gene combined to J kappa 1. Four are rearranged to the D21/9 D segment in the same reading frame, with CDRH3s of 16 to 17 amino acids. Three RFs (1 HID, 1 RA, and 1 MC) have CDRH3s differing by only three amino acids. The highly homologous V-regions in RFs from these two groups imply an initial selection to very similar, if not identical, epitopes. However, it remains to be seen whether somatic hypermutation alters the fine specificity of these autoantibodies.

[The association of the disease activity of rheumatoid factor positive vasculitis and the level of rheumatoid factor]

Rheumatoid factor (RF), an autoantibody against the Fc portion of denatured IgG, has long been recognized as an important biologic marker not only for rheumatoid arthritis but also for other auto-immune diseases. In this study, we measured the level of serum RF in four patients with RF positive systemic vasculitis using laser nephelometry. Three patients were diagnosed as polyarteritis nodosa and the other patient was diagnosed as systemic vasculitis without the finding of typical necrotizing vasculitis from biopsies. In the result, we found that the level of RF paralleled the disease activity in these cases. When active phase of the disease, the level of RF showed very high, and after the treatment combined with plasmapheresis, corticosteroid and immunosuppressive agent, the level of RF decreased in accordance with CRP, ESR and clinical features. These suggested that RF was the disease specific marker for RF positive vasculitis and beneficial informations for proper diagnosis and better treatment could be provided by measurement of the level of RF in patients with RF positive systemic vasculitis.

Uterine fluid human decidua-associated protein 200 and implantation after embryo transfer

Uterine fluid samples from 109 patients undergoing in-vitro fertilization and embryo transfer were obtained so as to examine the relationship between the uterine fluid concentration of human decidua-associated protein (hDP) 200 and the implantation rate. The sampling was performed on the day of embryo transfer with a Wallace catheter, used for the testing of cervical patency before embryo replacement. The implantation rate, as well as the pregnancy rate, demonstrated a significantly positive correlation with the concentration of hDP 200 in the uterine fluid, measured just before embryo transfer. These results indicate that hDP 200, identified as a rheumatoid factor secreted by the endometrium, may be involved in the implantation process.

[The clinical manifestations of Sjögren's syndrome in children]

Sjögren's syndrome (SS) is thought to be uncommon in children. We studied the clinical manifestations and laboratory findings of 12 pediatric patients with SS, all of children did not have sicca symptoms but have lymphocytic infiltration of salivary glands, abnormal sialograms or abnormal results of scintigraphy compatible with typical SS. Seven cases had primary SS and five were secondary SS and had other autoimmune disorders (three cases with systemic lupus erythematosus, one case with dermatomyositis, and the other with mixed connective tissue disease). All patients were female. The mean age at onset of symptoms, including other autoimmune manifestations, was 12.2 years (range 9-15 years). The initial symptoms were some systemic manifestations (fever, exanthema, arthralgia, etc.) and various autoimmune phenomena (butterfly rash, Raynaud's phenomenon, proteinuria, weakness of muscles, etc.). On the other hand, no patients complained sicca symptoms. Laboratory studies in our patients revealed elevated levels of IgG (92%), antinuclear antibody (92%), rheumatoid factor (58%), anti-SS-A antibody (75%). These findings were similar to those found in adult patients with sicca symptoms previously reported in literature. From these studies, we suggest that lip biopsy, sialography and/or salivary gland's scintigraphy should be carried out in patients who had abnormal laboratory findings as mentioned above, irrespective of absence of sicca symptoms, in order to diagnose SS at early period.

Malignant pheochromocytoma associated with Jaccoud's-type arthropathy, Raynaud's phenomenon, positive antinuclear antibody and rheumatoid factor

We describe a patient with malignant pheochromocytoma who developed Jaccoud's-type arthropathy and Raynaud's phenomenon as initial manifestations of malignant pheochromocytoma. Serologic findings included positive antinuclear antibody (ANA) and rheumatoid factor (RF) was also found in this patient. To our knowledge, this is the first time Jaccoud's-type arthropathy with positive ANA and RF has been reported as rheumatic manifestations of pheochromocytoma.

An isotype switched and somatically mutated rheumatoid factor clone isolated from a MRL-lpr/lpr mouse exhibits limited intraclonal affinity maturation

Employing site-directed mutagenesis we have reconstructed and expressed the germ-line precursor of an expanded rheumatoid factor (RF) clone. This RF clone, designated clone F, was isolated from an autoimmune MRL/MpJ-lpr/lpr mouse. Most of the clone members were extensively mutated and isotyped-switched. The predominant isotype of clone F was gamma 3. The RF bound specifically to the MRL gamma 2 a allotype (Igh-1j) but not to the B6 gamma 2a allotype (Igh-1b). The germ-line antibody was also found to bind gamma 2a in an RF assay. The affinities of the germ-line RF and representative members of the clone were measured in an ELISA-based equilibrium binding assay. The dissociation constant (Kd) of the germ-line RF was 2.5 x 10(-6) M. All of the expressed clone members had affinities within a two- to sixfold range of the germ line, indicating that the mechanisms of somatic hypermutation and selection resulted in only limited affinity maturation of this autoantibody clone.

Prevention of spontaneous polyarthritis in NZB/KN mice by treatment with a novel thiazole derivative, SM-8849

NZB/KN mice spontaneously develop polyarthritis, characterized by infiltration of inflammatory cells into the synovium and destructive damage of articular cartilage and bone. This study was performed to elucidate the effects of a novel thiazole derivative (SM-8849; (4-[1-(2-fluoro-4-biphenylyl)-ethyl]-2-methylamino thiazole) in comparison with the cyclooxygenase inhibitor, indomethacin, on disease development and immune disorders in NZB/KN mice. Mice were treated with SM-8894 (50 mg/kg) or indomethacin (2 mg/kg), starting from two months of age, for seven months. Indomethacin had no inhibitory effect on joint lesions in this model. In contrast, SM-8849 was effective in arresting the progression of arthritis, as confirmed by histologic and radiographic studies. Moreover, SM-8849, but not indomethacin, suppressed rheumatoid factor production. In addition, the population of CD5+ B cells in the peritoneal cavity and spleen was reduced with SM-8849 treatment. These findings suggest that NZB/KN mice are of use in the evaluation of intrinsic antiarthritic activity, independently of cyclooxygenase inhibition. Additionally, the therapeutic value of SM-8849 is strongly suggested by its efficacy in this model.

Monospecific but not polyreactive human hybridoma rheumatoid factors exhibit preferential binding specificities for IgG3 and IgG4

Among 38 human hybridoma-derived monoclonal rheumatoid factors (RFs) generated from patients with either rheumatoid arthritis (RA) or systemic lupus erythematosus (SLE), two groups of RFs can be identified. Monospecific RFs were derived primarily from patients with RA and are characterized by a binding specificity for IgG3 and/or IgG4. Polyreactive RFs were derived largely from patients with SLE and show a broader pattern of reactivity to all four isotypes of IgG. Neither population of RFs was exclusive to either disease. The binding specificities identified appear to be different from the RFs isolated from patients with mixed cryoglobulinemia and may reflect a different antigen selection mechanism.

The repertoire of rheumatoid factor-producing B cells in normal subjects and patients with rheumatoid arthritis

OBJECTIVE

To compare the B cell repertoire of normal individuals and patients with rheumatoid arthritis (RA) and, specifically, to identify precursor B cells with the potential to secrete rheumatoid factor (RF) and to understand the T helper cell requirements for the production of this autoantibody.

METHODS

Frequencies of precursors of IgM-, IgG-, and RF-producing B cells were measured in a limiting-dilution system. Two distinct sources of T cell help were compared. T cell help was provided by anti-CD3-activated CD4+ human T cell clones, or T cell-B cell interaction was facilitated by the bacterial super-antigen staphylococcal enterotoxin D (SED).

RESULTS

A subset of 2-14% of peripheral blood B cells secreted IgM and IgG in SED-driven cultures. The SED-responsive B cell subpopulation was present at 10 times higher frequency in normal donors compared with RA patients. However, the repertoires were very similar, particularly for RF+ precursors, which represented approximately one-third of all SED-responsive B cells. In normal individuals, most of these RF+ precursor B cells did not respond to anti-CD3-activated T helper cells, with only a very small fraction of B cells activated by anti-CD3-driven helper cells maturing into RF-secreting B cells (from 1 of 182 to 1 of 889 IgM-producing B cells). This subset was expanded approximately 50-fold in RA patients.

CONCLUSION

Normal subjects and RA patients share a pool of B cells which secrete RF when activated in the presence of SED and T helper cells. These B cells are frequent and obviously anergic in normal individuals. The B cell subset with the potential to produce RF when help is provided in noncognate T-B interaction (anti-CD3-driven T cells) is considerably expanded in RA patients, probably reflecting an increased responsiveness of such B cells to helper signals.

Generation and molecular analyses of two rheumatoid synovial fluid-derived IgG rheumatoid factors

OBJECTIVE

To study the Ig genes that encode IgG rheumatoid factor (IgG-RF) from rheumatoid synovial fluid.

METHODS

We used rheumatoid synovial fluid B cells to generate IgG-RF-secreting hybridomas. We then characterized their binding properties and determined their nucleotide sequences.

RESULTS

Two monospecific IgG-RFs were obtained. Sequence analysis of the RFs revealed a new V lambda gene family (designated V lambda 9) and extensive somatic diversification, including a duplication-insertion of 18 nucleotides (6 amino acid residues) into a hypervariable region.

CONCLUSION

The data provide further support for an antigen-driven response in the sustained production of potentially pathogenic IgG-RFs in rheumatoid synovium.

Serum rheumatoid factors in spinal cord injury patients

The rheumatoid factor (RF) levels of IgM-RF and IgG-RF types in sera from patients with spinal cord injuries (SCI) and osteochondrosis were investigated by ELISA. According to the findings in the late stages of the disease, SCI patients showed 46% seropositiveness for IgG-RF and 40% for IgM-RF. Patients with fresh central nervous system (CNS) injuries were 12% and 14% seropositive, respectively. Patients with osteochondrosis exhibited 33% seropositiveness for IgG-RF. The determination of serum RF enables us to identify the systemic body lesion in the SCI late stages as a rheumatoid disease. These data support the conclusion that RF determination is a reliable serological indicator of the severity of a patient's traumatic disease.

Rheumatoid factors

Rheumatoid factors (RFs) have been studied for over 50 years and are probably the most written about of any antibody. Nevertheless, the etiology of these RFs and the precise role they play in the pathogenesis of rheumatoid arthritis (RA) and juvenile rheumatoid arthritis (JRA) remain a major interest. When RFs participate in the generation of inflammation in RA and JRA, they probably do so by forming immune complexes (IC) or are themselves able to bring about the inflammatory response. Their presence has been associated with more severe disease, vasculitis, and systemic symptoms. The present review summarises the literature over the last few years on new and interesting findings on RF. This review covers an update on RF assays, RF cross-reactivity, specificity studies, immune complex formation, RF lymphocyte studies, and RF binding.

IgM rheumatoid factor and the inhibition of covalent binding of C4b to IgG in immune complexes

Work by other investigators has shown that IgM-rheumatoid factors (IgM-RF's) can impede complement-mediated inhibition of immune precipitation. We examined the binding of complement component C4b to radiolabelled IgG in model immune complexes and demonstrate that IgM-RF's are capable of reducing the covalent binding of C4b to 125I-IgG in the complexes. Reduced binding to IgG, however, may not be accompanied by binding of C4b to IgM-RF's within the complex, as we also demonstrate that IgM-RF's are relatively poor at C4b capture compared with normal IgM.

Interplay of T lymphocytes and HLA-DR molecules in rheumatoid arthritis

One of the genetic components of seropositive rheumatoid arthritis has been mapped to a short sequence stretch in the third hypervariable region of the HLA-DRB1 gene. A new concept has emerged, proposing that the shared-sequence motif is functional in determining the clinical patterns of rheumatoid arthritis and the severity of the disease in a codominant mode. Patients with a double dose of the shared sequence tend to have more serious disease manifestations, suggesting a model in which the genetic element is involved in perpetuating the disease. The pathogenetic model in which the shared epitope selectively binds and presents an arthritogenic peptide appears too simplistic to account for these findings. Our understanding of how the shared epitope may contribute to forming the molecular complex of the T-cell receptor, peptide, and HLA-DR molecule is advancing. Molecular analyses of the synovial T-cell infiltrate continue to define the various components involved in recruiting T cells to the site of synovial inflammation. Adhesion molecules, predominantly the endothelial cell ligands vascular adhesion molecule 1 and endothelial leukocyte adhesion molecule 1, attract phenotypically selected T cells with a wide spectrum of specificities. The rheumatoid factor-positive B cells may be important antigen-presenting cells in the joint and may activate T cells with many different specificities. Rheumatoid factor immunoglobulin genes show clear evidence of somatic mutation, indicating a T cell-dependent, antigen-driven process. Thus, multiple factors contribute to the composition of the inflammatory infiltrate and may well modulate the repertoire of T cells recruited to the tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Rheumatoid arthritis with monoclonal IgE rheumatoid factor

We studied a patient with rheumatoid arthritis (RA) and a high titer of IgE that could be attributed to a mono or oligoclonal expansion of IgE+ B lymphocytes. These IgE had no specificity for known allergens but bound to a panel of self (including Fc fragment of IgG) and exogenous antigens, displaying properties typical of polyspecific antibodies. We concluded that (1) RA can be associated with increased amounts of polyspecific IgE antibodies; (2) clonal excess populations of B cells are not a unique feature of malignant lymphoma, but may occur in autoimmune diseases in the form of a benign oligoclonal B cell proliferation.

Monoclonal IgM, IgG, and IgA human rheumatoid factors produced by synovial tissue-derived, EBV-transformed B cell lines

In an effort to study disease-related autoantibodies in rheumatoid arthritis (RA), rheumatoid factor (RF)-producing B cell lines were developed from the heterogeneous B cell populations infiltrating the synovial tissue of patients with arthritis. Over 125 EBV-transformed B cell cultures were derived from three patients: one with early pre-erosive RA, one with advanced RA, and one with osteoarthritis (OA). IgM, IgG, and IgA RF-producing B cell lines were found in all three series but with several significant differences. In each of the two RA patients, 22% of the Ig-producing cell lines secreted RF compared to 7% in the OA patient. The isotypes of these RF were mostly IgM in the early RA (62%) and the OA patient (60%) as contrasted to predominantly IgA (75%) and, to a lesser extent, IgG (12.5%) in the advanced RA patient. Analyses of the light (L) chain composition of these RF revealed that 82% of the IgM RF used kappa L chains whereas only 31% of the non-IgM RF used kappa chains. Antigen-binding analyses of these RF revealed that all the synovial tissue-derived RF from the advanced RA patient exhibited antigen binding specificities restricted to a narrow range of gamma globulins. In contrast, the synovial RF of the other two patients were either reactive with a broader spectrum of gamma globulins or reactive with a variety of unrelated antigens. In every instance, the gamma globulin-specific RF were of all three major isotypes whereas the polyreactive RF were restricted to the IgM isotype. These data demonstrate that synovial B cells from both RA and OA patients can produce RF and that significant differences can exist among patients in the percentage of RF generated and their H and L chain isotype distribution. The reversal of the kappa:lambda ratio among the IgG and IgA RF and the more restricted antigen-binding specificities of the IgG and IgA vs IgM RF suggest that a non-stochastic, possibly antigen-driven selection process was involved in their generation. The relevance of these differences in RF precursor frequency, H and L chain distribution, and antigen specificity to these two diseases warrants further investigation.

[Immunological studies of thrombotic thrombocytopenic purpura]

We studied the immunological changes in eight cases of thrombotic thrombocytopenic purpura (TTP). At autopsy, one case showed IgM deposition in the walls of the capillaries of heart and spleen. Coombs' test was negative in all cases and rheumatic factor was positive in four of eight cases. Anti-nuclear factor was positive in three cases including one case showed positive only during remission. One case, who was diagnosed as TTP complicated with systemic lupus erythematosus (SLE) showed some serological abnormalities for LE test, anti-streptkinase, anti-DNA antibodies, platelet bound IgG, and serum level of IgG by renal biopsy. There were little changes in complements levels. Platelet associated IgG (PAIgG) was positive in four of six cases, and this seemed to be the only abnormality associated with remission and relapses of TTP.

Prevalence of thyroid abnormalities in patients with rheumatoid arthritis

The prevalence of thyroid abnormalities was determined in 131 patients: group I = rheumatoid arthritis, 68 patients, group II = systemic immunological diseases (IIa Sjögren's syndrome, n = 6; IIb other rheumatic autoimmune disease, n = 17), group III = other rheumatic diseases n = 13 and control group (n = 27). Thyroid abnormalities (hypo, hyperthyroidism, nodular goiter) were frequent: 33.8% in group I, 100% in group IIa, 11.7% in group IIb. Hypothyroidism was present in 19.1% (group I), 50% (group IIa). 6% (group IIb). Autoimmune thyroiditis was found in 16.2% in group I, 100% in group IIa, 11.7% in group III. Thyroid diseases are frequent in patients with rheumatoid arthritis. Therefore thyroid tests might be performed in patients with rheumatoid arthritis.

IgA rheumatoid factor in mucosal fluids and serum of patients with rheumatoid arthritis: immunological aspects and clinical significance

In order to gain insight into the production and clinical significance of IgA rheumatoid factor (IgA-RF) in mucosal fluids of patients with rheumatoid arthritis (RA), we examined tear fluid, saliva and serum from 80 patients with RA. Significant correlations were found between IgA-RF levels in tear fluid and saliva (P = 0.002, r = 0.57), saliva and serum (P < 0.001, r = 0.79), and serum and tear fluid (P < 0.001, r = 0.31). No significant correlations were found between total IgA levels in these fluids. Comparison between circulating and mucosal IgA-RF levels after correction for total IgA, revealed that mucosal IgA-RF levels are on average 2.5 times higher than circulating IgA-RF levels. Analysis of IgA-RF specificity showed that lacrimal and salivary IgA-RF reactivity with various IgG subclasses is similar and differs from serum IgA-RF specificity. These results indicate local production of IgA-RF in salivary and lacrimal glands and support the view of a common origin of IgA-RF producing B cells present in mucosal tissues. Mucosal and circulating levels of IgA and IgA-RF were not associated with tests that quantify tear fluid production. This indicates that mucosal and circulating levels of IgA and IgA-RF in patients with RA cannot be regarded as markers for the development of secondary Sjögren's syndrome.

The immunoregulation of rheumatoid factor by the CD8 T lymphocyte subset in rheumatoid arthritis

Flow cytometric analysis on 81 peripheral blood samples from patients with rheumatoid arthritis (RA) showed that levels of serum IgM rheumatoid factor (RF) were associated with the CD8+ cell level. A significant elevation of natural killer (CD56) cell levels was also observed in RA peripheral blood. Using in vitro antibody production techniques, CD8+ cells from patients with RA appeared to act as suppressors of RF production. Paired blood and synovial fluid samples from 9 patients with RA indicated a significant increase in SF CD8+ cells and DR+ T cells over the corresponding peripheral blood levels. The data suggest that CD8+ cells in RA may respond to immunological abnormalities occurring during the course of the disease.

Interleukin-8 in inflammatory rheumatic diseases: synovial fluid levels, relation to rheumatoid factors, production by mononuclear cells, and effects of gold sodium thiomalate and methotrexate

The content of interleukin-8 (IL-8) in the synovial fluid and its production by blood and synovial fluid mononuclear cells (PBMC and SFMC) was compared in rheumatoid arthritis (RA) and various other inflammatory rheumatic disorders. The study included 125 patients and 20 healthy individuals. The highest concentrations of IL-8 were found in the synovial fluids and culture supernatants of PBMC and SFMC from patients with seropositive RA. Only PBMC from seropositive patients, and not from other rheumatic diseases, exhibited significant spontaneous release of IL-8 that correlated with serum IgM rheumatoid factor titers. Gold sodium thiomalate (GST) and methotrexate (MTX) inhibited the spontaneous and stimulated IL-8 production by PBMC by 55-86% at 50 and 10 micrograms/ml, respectively. Two main conclusions were drawn: (1) rheumatoid factors appeared to be a major cause of enhanced IL-8 production in seropositive RA, and (2) inhibition of IL-8-mediated neutrophil migration and activation could be part of the mechanism of action of GST and MTX.

Rheumatoid factor activity in serum and bronchoalveolar lavage fluid from patients with acute hypersensitivity pneumonitis

The presence of rheumatoid factor was detected in both serum and bronchoalveolar lavage fluid (BALF) from patients with acute pigeon breeder's disease. IgM rheumatoid factor was positive in 14 of 20 serum samples and 6 of 20 BALF samples by ELISA. In contrast, negative results were found in 20 healthy subjects with a history of avian antigen exposure, as well as in the serum and BALF from 10 normal subjects. The simultaneous presence of rheumatoid factor in serum and BALF occurred in five patients, and four of them revealed high levels of rheumatoid factor in BALF in comparison with serum determinations. These abnormalities may play an important role during the acute inflammatory reaction in hypersensitivity pneumonitis.

The immunoglobulin kappa light chain repertoire expressed in the synovium of a patient with rheumatoid arthritis

OBJECTIVE

To analyze the nature of the B cell response in the synovial tissue of a patient with rheumatoid arthritis (RA). Specifically, we sought to determine if the pattern of immunoglobulin expression was consistent with polyclonal stimulation of B cells or an antigen-driven response.

METHODS

We generated an unrestricted complementary DNA (cDNA) library from the diseased synovium of a rheumatoid factor (RF)-positive patient with an 18-year history of RA. A random sample of kappa light chain recombinants was identified, and sequence analysis was performed. The variable domains were compared with an extensive database of germline and cDNA kappa sequences.

RESULTS

We found a light chain repertoire enriched for kappa transcripts containing 2 V kappa gene segments (Humkv325 and Humkv328) that are frequently associated with paraproteins expressing RF activity. Kappa variable domains from synovium contained numerous somatic mutations which resulted in frequent replacement of amino acids that encode the classic antigen-binding site. Unexpectedly, many of these kappa transcripts contained non-germline-encoded nucleotides (N regions) at the site of V kappa-J kappa joining. The combination of N-region addition and variation in the sites of V kappa-J kappa splicing generated unusually long complementarity-determining region 3 regions and charged amino acids near the V kappa-J kappa splice site.

CONCLUSION

The pattern of somatic mutations found in this patient sample supports the hypothesis that these synovium-derived plasma cells are the product of immunoglobulin receptor-dependent (i.e., antigen-driven) selection. The extent of N-region addition raised the additional possibility that these antibodies derive from an unusual set of B lymphocytes that have escaped normal regulation.

[Clinical significance of rheumatoid factor--its complement activating property and isotype]

We investigated the relationship between complement-activating properties of rheumatoid factors (RF) and their isotypes. Active and inactive RA patients without extra-articular symptoms (EAS) and those with EAS were studied. Patients with SLE, liver cirrhosis (LC) and normal volunteers were served as controls. Isotype of RF was measured by ELISA and complement activation (CA) of RF was measured by hemolytic assay. The CA values were significantly higher in RA patients with EAS than those in RA patients without EAS and with other diseases. The IgG and IgM-RF values were significantly higher in active RA without EAS than in inactive RA. Positive correlations between IgM-RF values and CA values were observed in RA with or without EAS, SLE and LC. The Sephadex G-200 gel filtration analysis of sera revealed CA in only 19S IgM fraction. Additionally, we purified 19S IgM-RF from sera of RA, SLE and LC patients by affinity chromatography, and found 19S IgM-RF had CA. These data suggest that serum IgM-RF may play a critical role in the pathogenesis of RA, especially in RA with EAS.